On the probability of formation of intermetallic compounds in dissimilar welded joints obtained by friction stir welding

The article describes the mechanisms and causes of the occurrence of intermetallic phases during friction stir welding of dissimilar joints. The nucleation and growth of intermetallic phases for a pair of dissimilar metals to be welded under comparatively favorable time and temperature conditions of the FSW is facilitated by the atomic-vacancy environment, which is responsible for the continuous atomic-structural bond and mass transfer of accumulated atoms in local regions of the welded joint with an equiaxial grain lamella-shear structure of the welded core. compounds with a concentration close to critical, combined with others in a superplastic state. In the process of forming a welded joint under the influence of a moving and rotating welding tool, the lamellae are subjected to bending and torsional stresses with simultaneous tension, causing them to generate point defects and especially a large number of various types of dislocations, triggering the formation of edge dislocations in the lamellae, which are lined up in the process into dislocation walls, dividing lamella grains into separate fragmentary subgrain boundaries, along which the processes of fragmentation and dispersion develop. This phenomenon is explained by the fact that the processes of fragmentation and dispersion of IMP lead to the composition of the nugget of the welded joint by fragments, often nano-sized fragments of various configurations, which act as hardeners of the weld nugget matrix.

Exergy Analysis of an Ejector Cooling System by Modified Gouy–Stodola Equation

In this paper, exergy destruction analysis of a heat-assisted ejector cooling system has been carried out using a modified Gouy–Stodola equation. The modified Gouy–Stodola equation provides a more accurate and realistic irreversibility analysis of the system than the conventional Gouy–Stodola formulation. The coefficient of structural bond (CSB) analysis has also been executed to find the component whose operating variables affect the system’s total irreversibility at the most. Exergy analysis revealed that the maximum exergy loss happens in the ejector followed by the generator and condenser. The model predicted 40.84% of total irreversibility in the ejector at the designed conditions. However, total exergy destruction is found to be the most sensitive to the evaporator temperature. The CSB value of 12.97 is obtained in the evaporator using the modified exergy method. The generator appears to be the second sensitive component with the CSB value of 2.42, followed by the condenser with the CSB value of 1.628. The coefficient of performance of the system is found to be 0.18 at the designed conditions. The refrigerant R1234yf is considered in the system.

π‑Extended Boron Difluoride [NՈNBF2] Complex, Crystal Structure, Liquid NMR, Spectral, XRD/HSA Interactions: A DFT and TD-DFT Study

The novel tetrahedral 10-(4-carboxyphenyl)-2,8-diethyl-5,5-difluoro-1,3,7,9-tetramethyl- 5H-di-pyrrolo[1,2-c:2',1'-f][1,3,2]diazaborinin-4-ium-5-uide [NՈNBF2] BODIPY complex was prepared in a very good yield and via one-pot synthesis. The desired [NՈNBF2] has been used as a model complex for XRD/HSA interactions and DFT/B3LYP/6-311G(d,p) computations. The tetrahedral geometry around the boron center was demonstrated by DFT optimization and XRD-crystallography. The 1H, 11B, and 19F-NMR spectra were used also to support the high symmetrical BODIPY via π‑extended phenomena. Moreover, the values of the DFT-calculated structural bond lengths/angles and DFT-IR were matched to the corresponding experimental XRD and IR parameters, respectively. The crystal lattice interactions were correlated to Hirshfeld surface analysis (HSA) calculations. Calculations of the Mulliken Atomic Charge (MAC), Natural Population Analysis (NPA), Global reactivity descriptors (GRD), and Molecular Electrostatic Potential (MEP) quantum parameters were performed to support the XRD/HSA interactions result. Analysis of the predicted Density of States (DOS), molecular orbital, and time-dependent density functional theory (TD-DFT) calculations have been combined to explain the experimental UV-vis spectra and electron transfer behavior in [NՈNBF2] complex using MeOH and other four solvents.

Support for Marginalized Children: Influences of Micro and Meso Contexts on Socially Just Principal Practices

This qualitative case study research examines the perceptions of three U.S. principals as they work for social justice in the school level meso context as enacted through the lens of their micro contextual values and beliefs. Through interviews with three rural high school principals, we look to the influence of context on decision making through a study of the principals’ articulations of the role of context in supporting or hindering their work for marginalized children. Findings from this study point to the culture of the community in which the school was situated and the challenges sometimes associated with the community as the most mentioned meso factor that guided the principals’ practice. The micro context of the leader’s personal story was a testament to what they valued and how they enacted these values as a leader for social justice. The study concludes with a model which reconceptualizes the macro, meso, and micro relationships not as a directional relationship that indicates the influence of one context onto another, but as a structural bond suggesting interdependency.

Structure determination, vibrational bands and chemical shift assignments of 3-(4-(3-(2,5-dimethylphenyl)-3-methylcyclobutyl)thiazol-2-yl)-2-(o-tolyl)thiazolidin-4-one: A combined experimental and quantum chemical density-functional theory studies

This paper report is an analysis of the title compound by means of X-ray crystallography, FT-IR, NMR and DFT calculations, in the context of structural and spectral characterization. The crystal and molecular structures of the compound were determined by single-crystal X-ray diffraction (SCXRD). Fourier Transform Infrared (FTIR) spectrum was recorded in the range from 400 cm–1 to 4000 cm–1. The 1H and 13C nuclear magnetic resonance (NMR) spectra were also recorded. DFT calculations were employed to support X-ray molecular geometry and calculate IR and NMR (1H and 13C) spectral bands. The structural (bond lengths, bond angles, torsion angles) and spectral (vibrational modes and chemical shifts) parameters obtained from DFT levels (B3LYP/6-31G(d,p) and B3LYP/6-31G+(d,p)) were compared with experimental findings, and an excellent harmony between the two data was ascertained.

The Sacramental Nature of Medicine

There is an underlying structural bond between medicine and religious monotheism. There are shared assumptions, values, and institutional structures that create a deep underlying unity between these two spheres. There are five broadly shared connections between secular medicine and the monotheistic religions—especially akin to Jewish and Christian traditions—where medicine and religion mirror one another in values and structures. These five points of connection include sickness/sin, the role of the healing mediator, therapy, patient disposition, and the healing milieu. When the spheres of medicine and religion become overtly disconnected from one another as partners, as now is the case in secular medicine, medicine rises perilously to the level of a functional-like religion. While contemporary medicine attempts to be consciously neutral toward traditional religions, medicine’s internal structures mirror deeper religious concepts, in tension with secular interpretations.

Hypercoordinate β-carbon in Grubbs and Schrock olefin metathesis metallacycles

From the analysis of structural, bond order, electron density and 13C NMR data of a large variety of ruthenacyclobutanes and tungstenacyclobutanes, we show that the Cβ of the metallacycle is pentacoordinate.

EXERGY ANALYSIS OF A VAPOR COMPRESSION–VAPOR ABSORPTION CASCADE SYSTEM

In this paper, second law analysis has been done for the vapor compression–vapor absorption (VC–VA) cascade system. Ammonia–water is considered as the working pair in absorption section and R407C is dealt as the working fluid in VC section. Exergy destruction or the irreversibility rate is determined in each components of VC–VA cascade system, for a wide range of cooling capacity by considering a variable speed reciprocating compressor. Further in this, Coefficient of structural bond (CSB) analysis is carried out to quantify the effect of varying the generator temperature, effectiveness of solution heat exchanger, inlet temperature of external fluids in evaporator/condenser and some other variables. Solution heat exchanger and the condenser are reported to have high CSB value, so have a great scope of improvement to reduce the irreversibility rate of the whole system.